1. Field of the Invention
The present invention relates to printing devices. More concretely, the invention relates to a machine for printing different polygraphic matter, both simple and highly artistic.
2. Description of the Related Art
Printing machines are known comprising a printing form in the form of a stencil applied on a mesh, means for applying ink onto the form and means for forcing the ink through cells of the stencil to deposit the ink on the surface of the material being imprinted. In a known machine, disclosed in Japanese Application No. 55-34970, class B41M 1/12, published Mar. 11, 1980, the printing form is made in the form of a mesh covered with a layer of light-sensitive emulsion. Upon exposure of the emulsion through a photoform under the effect of UV radiation, the emulsion is hardened in the space portions of the mesh in the desired pattern. The unhardened portions of the emulsion are washed off. The hardened emulsion is subjected to setting by thermal treatment and is covered with a special composition to protect it against acids or alkalis.
In the process of printing, ink is applied to the form and is forced through the open cells of the mesh by a doctor blade to be transferred to the paper. After the printing is finished, hardened emulsion that was formed on the mesh is removed, and the mesh is again covered with a new layer of light-sensitive emulsion to prepare the next stencil.
A disadvantage of such machines is the necessity of making and setting up a printing form in order to print each run. This process is lengthy, per se. Furthermore, the trend in present-day polygraphy is characterized by small runs of publications, which causes the time necessary to prepare a machine for operation to become comparable to the time actually spent on printing. Thus, expensive equipment is used ineffectively.
In another prior art printing device, such as that disclosed in Browning et al., U.S. Pat. No. 3,798,365, ink is coated onto a printing form including a mesh having a plurality of cells. Ink is thermally ejected from selected cells onto the recording medium by sweeping a light beam across the mesh cells. The light beam heats up the entire volume of ink contained in a cell so as to evaporate the carrier liquid, whereupon the remaining ink particles are scattered onto the recording medium in a dry and heated state.
In scanning the light beam across the printing form, the disclosed apparatus controls whether or not ink is ejected from each cell by modulating the intensity of the light beam between a level capable of heating the ink carrier liquid to evaporation and a level which is not capable of such heating.
Because heat is used to release the ink from the mesh cells, the type of printing device disclosed in Browning is only capable of printing at a resolution of approximately 100 dpi, which is extremely inadequate for modern day printing applications.